Mon-Af-Po1.11-06 Operation of the helium cryogenic system for the hybrid magnet at CHMFL J. , Y. , Z. , H. Li, Q. Meng, L. Shi, X. , M. , X. Chen and D. Kuang High Magnetic Field Laboratory, Chinese Academy of Sciences. Hefei 230031, China. Background Summary The hybrid magnet which consists of a 34 T resistive insert and 11 T superconducting outsert has been put into operation early this At CHMFL, construction and commissioning of the helium cryogenic system which have the functions of liquid helium production and hybrid magnet cooling is year at the High Magnetic Field Laboratory of the Chinese Academy of Sciences (CHMFL). The superconducting outsert made of Nb3Sn finished. At 4.5 K, the field of the hybrid superconducting outsert is increased to 10 T, and combined with the water-cooled magnet, 40 T in a 32 mm clear bore cable-in-conduit conductor (CICC) technology is designed to provide 11 T field in 800 mm room temperature bore. The is obtained. The helium cryogenic system achieves the expected performance. Thermal-hydraulic measurement and control under magnetic and cryogenic superconducting coils whose total cold mass is 11 tonnes are cooled with forced flow supercritical helium at 4.5 K. condition also give satisfactory results. For the target of 45 T field in this year, Perfection of each sub-system including helium cryogenic system is processing. About the CHMFL The hybrid magnet The helium cryogenic system Magnets we have: Combined Field Operating Coil Clear The main missions of the Lab: WM1 38.5T@32mm system contribution temperature /conductors bore

1）Develop series of high field magnets Water

(hybrid magnets, superconducting magnets WM2 25T@50mm SM 11T 4.5 K CICC 800mm WM 34T RT Florida Bitter 32mm magnets and water-cooled magnets) - 2 ） Research on physics, functional cooled WM3 20T@200mm material, chemistry, life sciences and WM4 27.5T@32mm pharmacology in the extreme high WM5 35T@50mm

magnetic field Superconducting

SM1 8T@100mm magnets SM2 20T@50mm SM3 18.8T@54mm hybrid magnet

SM4 9.4T@400mm magnets Hybrid Cryo-distribution box HM1 45T@32mm LHe plant (360W at 4.5 K or 110 L/h has been operated LHe production for 5 years Cryogenic circuits Cooldown Commissioning and operation

recovery line 300 80 B65 coilA B66 SV43 GHe return to compressor suction side A inlet SV42 A outlet 70 coilB NV59 250 coilC cold helium from coldbox B inlet NV58 60 coilD FV23 warm helium form compressor B outlet 200 C inlet FV24 50 GHe return to coldbox C outlet /compressor suction side

FCV608B D inlet

FCV616 40 FCV611B 150

D outlet mobile dewars 30 recovery line Temperature (K) 100 20 HV346 FCV607 50 FV21 FV22 FCV611A 10

Maxmium temperature differences (K)

FCV606 FCV608A 0 0 0 50 100 150 200 250 300 350 400 450 500 550 0 50 100 150 200 250 300 350 400 450 500 550 Time (hour) Time (hour) 4.2 K helium bath 15 40

35 12 total 30 coil A coil B 25 coil C 9 pressure differences FCV604 coil D The maximum temperature of the coils is below 5.0 K when stand-by, and when the hybrid magnet is FCV603 FCV602 FCV601 inlet pressure 20

outlet pressure operating at 40 T field, the value is 5.3 K. The total Pressure differences is 3.5 bar in operation. coil D coil C coil B coil A 6 15

Mass flow rate (g/s) Pressure (bar abs) 10 frame_bottom frame_top 3 5 Magnetic affection on the components:

0 0 Magnetic shields are covered to the positioner of each cryogenic valves to avoid magnetic affection. HTS CL 1 0 50 100 150 200 250 300 350 400 450 500 550 0 50 100 150 200 250 300 350 400 450 500 550 The frour sub-coils are totally divided into 26 cooling-channels Time (hour) Time (hour) Turbo molecular pump and vacuum gauges are also shielded. HTS CL 2 which are hydro-dynamically connected in parallel. It takes 23 days to cool down the superconducting outsert to 4.5 K. The Measurement deviation happens to some CLTS thermometers and capacitance LN2 level probe. Calibration or replacement is needed after operation. All system assembly work was finished at September, 2016. process is divided into three phases: 300-140 K, 140-20 K and 20-4.5 K.